CI

At a glance

ClinicalIndex Comparison Record
Phase 3Active· 1,244 enrolled
Drug / intervention
Pembrolizumab +2 morebiological
Likely dose
Not stated in record
Structured eligibility isn't available for this trial yet — see the full criteria in the Eligibility tab below.

Standardized by ClinicalIndex from the ClinicalTrials.gov record · verify against the source.

Search/NCT03834493
NCT03834493Phase 3Active

A Phase 3, Randomized, Double-blind Trial of Pembrolizumab (MK-3475) Plus Enzalutamide Versus Placebo Plus Enzalutamide in Participants With Metastatic Castration-Resistant Prostate Cancer (mCRPC) (KEYNOTE-641)

Merck Sharp & Dohme LLC·interventional·Posted Feb 8, 2019·Updated Jul 18, 2025

In Brief

A Phase 3 clinical trial evaluating Pembrolizumab, Enzalutamide, and 1 other intervention for Prostatic Neoplasms. Active but no longer recruiting, targeting 1,244 participants across 259 sites in 28 countries.

Detailed Summary

The purpose of this study is to assess the efficacy and safety of the combination of pembrolizumab (MK-3475) and enzalutamide in the treatment of men with metastatic castration-resistant prostate cancer (mCRPC) who have not received chemotherapy for mCRPC, are abiraterone-naïve, or are intolerant to or progressed on abiraterone acetate. There are two primary study hypotheses. Hypothesis 1: The combination of pembrolizumab plus enzalutamide is superior to placebo plus enzalutamide with respect to Overall Survival (OS). Hypothesis 2: The combination of pembrolizumab plus enzalutamide is superior to placebo plus enzalutamide with respect to Radiographic Progression-free Survival (rPFS) per Prostate Cancer Working Group (PCWG)-modified Response Evaluation Criteria in Solid Tumors Version 1.1 (RECIST 1.1) as assessed by blinded independent central review.

Study Details

Study Typeinterventional
Allocation--
Masking--
Primary Purpose--
CountriesArgentina, Australia, Austria, Brazil, Bulgaria, Canada, Chile, Colombia, Czechia, France, Germany, Hungary, Ireland, Israel, Italy, Japan, Netherlands, New Zealand, Poland, Puerto Rico, Russia, South Korea, Spain, Taiwan, Turkey (Türkiye), Ukraine, United Kingdom, United States
Collaborators--

Timeline

Phase 3ActiveOverdue
20192020202120222023202420252026
First PostedFeb 8, 2019
Enrollment StartJul 28, 2019
Primary CompletionDec 12, 2022
Study CompletionMay 29, 2026
TodayJul 2, 2026
Enrollment to primary: 3.4 yearsPosted 7.4 years ago

Interventions

Pembrolizumabbiological

IV infusion

Enzalutamidedrug

Capsules/Tablets

Placebodrug

IV infusion